[GreenKeys] Loop Supply

[Robert Downs]

That is correct.  Pulling magnets only work at 60 mA when in series (each
magnet has 60 mA flowing through it).  If you wire the magnets in parallel
and adjust the loop current back to 60 mA, you will only have 30 mA flowing
through each magnet, and the machine will probably run open.  And don’t ask
me why it is 60mA and 20mA instead of 60mA and 30mA with the holding magnets
as I don’t recall but assume that it must have to do with the different
magnetic field magnitude rise and fall times .

 

Robert Downs

 

From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Xavier Andrieu via
GreenKeys
Sent: Friday, December 14, 2018 14:59
To: 'John, W9DDD'; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Loop Supply

 

My understanding was that selectors with "pulling magnets" can only be used
at 60 ma and selectors with "holding magnets" can be wired in series or in
parallel and then run either 60 ma or 20 ma. (see
www.baudot.net/gil/tty-machines/M15-KSR.htm).

 

Xavier

 

De : greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] De la part de John, W9DDD
Envoyé : vendredi 14 décembre 2018 21:34
À : greenkeys at mailman.qth.net
Objet : Re: [GreenKeys] Loop Supply

 

I'm foggy about the specifics of the 15 (about 57 years of cobwebs), but you
show in your drawing what appears to be magnets wired in series instead of
parallel, which would be normal for 60ma.  You can go 30ma with parallel
connection, normal was 20.  

John, W9DDD
 
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